/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 666
 * Date: 2022-11-26
 * Time: 22:50
 */
public class test {
    public static void main(String[] args) {
        String a="uuuQQQQ";
        System.out.println(a.isEmpty());
        System.out.println(a.toLowerCase());
        System.out.println(a.toUpperCase());
        System.out.println(a.substring(3));
        System.out.println(a.charAt(1));
        String[] s = a.split("");
        System.out.println(s[1]);
        StringBuilder b;
    }
}
